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Date: Fri, 15 May 2015 09:00:27 +0200
From: Christian Borntraeger <borntraeger@de.ibm.com>
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Subject: Re: [Qemu-devel] [PATCH v2] block: Let bdrv_drain_all() to call
 aio_poll() for each AioContext
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To: Alexander Yarygin <yarygin@linux.vnet.ibm.com>, qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, qemu-block@nongnu.org, Ekaterina Tumanova <tumanova@linux.vnet.ibm.com>, Stefan Hajnoczi <stefanha@redhat.com>, Cornelia Huck <cornelia.huck@de.ibm.com>, Paolo Bonzini <pbonzini@redhat.com>

Am 15.05.2015 um 08:59 schrieb Christian Borntraeger:
> PS: There is another independent issue now in the kernel when exiting QEMU
> caused by Linux kernel commit 6098b45b32e6baeacc04790773ced9340601d511
> Author:     Gu Zheng <guz.fnst@cn.fujitsu.com>
> AuthorDate: Wed Sep 3 17:45:44 2014 +0800
> Commit:     Benjamin LaHaise <bcrl@kvack.org>
> CommitDate: Thu Sep 4 16:54:47 2014 -0400
> 
>     aio: block exit_aio() until all context requests are completed
> 
> A QEMU with 1000 devices will sleep a long time in exit_aio with now obvious
> sign of activity as zombie process. I will take care of that....
> 
> Christian

To make it clear. This kernel wait time happens with and without Alexanders patch.